The present invention relates to an annular plastic wheel mounted on a bearing, and particularly to means which stiffen such a wheel, yet enable it to have a smooth, non-undulated outer peripheral travel surface over which a belt, or the like, is trained.
The annular wheel rotates around a stationary hub, and an annular bearing is disposed between the rotating wheel and the hub. To strengthen the plastic wheel, radially extending stiffening ribs are disposed at spaced intervals around the wheel. The width of the ribs in the axial or width direction of the wheel is typically less than the width of the peripheral travel surface of the wheel.
Plastic wheels of this type are well known. They are used, for instance, as tensioning rollers in various fields. Over time, increasingly greater demands are being made, particularly on the peripheral travel surfaces of the wheels. At the circumferential locations around the travel surface at which the radial ribs are located, undulations are produced upon manufacture of the wheels, particularly due to the presence of the stiffening ribs. The undulating surfaces can have negative effects on a system provided with the tensioning rolls, particularly when the wheels rotate at high speeds.